[70.09] Dust Clouds surrounding the Galilean Satellites

Dust clouds of the Galilean satellites Ganymede, Europa and
Callisto have been detected in-situ with the Galileo dust
detector. The dust grains have been sensed at altitudes
below several satellite radii. We identify the particles
originating from the satellites by their impact direction,
impact velocity, and mass distribution. These data imply
that the grains have been kicked up by hypervelocity impacts
of micrometeoroids onto the satellites' surfaces. We
calculate the radial density profile of the particles which
would be ejected from the satellite by interplanetary and
interstellar dust grains, assuming the yields, mass and
velocity distributions of the ejecta obtained from
laboratory impact experiments onto icy targets and
considering the dynamics of the ejected grains. Dust
measurements in the vicinities of satellites by spacecraft
detectors are a beneficial tool to obtain more knowledge
about the satellite surfaces, as well as dusty planetary
rings maintained by satellites through the impact ejecta
mechanism. Such an ejection process has been suggested as
being responsible for maintaining both the Jovian ring and
Saturn's E ring.

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